Study On An Internet Filter Model Based On Bypass

With the development of Internet, there is more and more illegal information in network. It is necessary to filter and control the illegal information. There are two filter modes at present: filter mode of based series, filter mode of based client filter software. We design the filter mode based bypass for the localization of the two filter modes. The filter mode will filter and control the illegal information of Internet, and give users a healthy and clean network environment. The filter system based bypass is called Internet Content Intelligent Control System. The system consists of front server and policy server and policy manage server. The policy manage server is used to manages the filter policy of the whole filter system, and classes the URL from search engine. The policy server is used to set users' individual filter policy and gets URL class information and policy setting information from the policy manage server synchronously and timely. The policy server synchronizes the information to the front server. The front server controls and filters the users bases of the control information. The front server consists of packet capture module and protocol analysis module and reaction modules. When a user browses an illegal web, the front server captures the access packet firstly because of the front server and client are in the local area network. The front server analyses the packet' protocol and data, and then responses for it bases of policy setting and filter lists. The front server simulates server and transfers RST packet to client from bypass. The client will cut off the TCP link with the server after it receives the RST packet, the TCP "three-way handshake" between the client and the server is paused. So the users can't browse the Web information. The front server controls and filters Internet information bases of destroying the TCP "three-way handshake".